Windows 11 25H2 Update: Disk Shows Unallocated

Updated on Nov 8, 2026 | by Qiling

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Why a Partition Appears Unallocated
Check Before You Create Anything
Protect the Data First
Scan the Space with Qiling
Frequently Asked Questions

When a disk that worked before the Windows 11 25H2 update suddenly appears as unallocated in Disk Management, the volume has usually not been erased. The update restarted the storage stack, and the partition table or file system is now being misread. The data is still on the platters or NAND until new writes reach it.

Why a Partition Appears Unallocated

Unallocated means Windows sees no valid partition entry at that position on the disk. The cause can be a damaged partition table, a partition entry that lost its type or offset, or a disk that was re-enumerated with a different sector size after the update.

A second pattern is a volume that still exists but shows as RAW. In that case the partition entry is intact and the file system is unreadable. The distinction matters: an unallocated disk needs partition-level recovery, while a RAW volume needs file-system-level recovery.

Do not initialize the disk and do not create a new partition over the unallocated space. Both actions write a fresh partition table and can destroy the metadata that recovery tools need to rebuild the old volume.

Check Before You Create Anything

Open Disk Management and note whether the space is labelled Unallocated, RAW, or Healthy without a drive letter. A healthy volume without a letter only needs a new letter, which is the simplest case and does not involve recovery software.

Check the disk number and capacity against the physical label. On a laptop with two similar NVMe drives, working on the wrong disk is easy and the result is irreversible. Unplug external drives you do not need so that only the affected disk remains.

Stop using the machine for downloads, updates, or new documents until you have recovered the files. Every write can reuse the space that still holds the old partition metadata.

Protect the Data First

If the disk still appears in the firmware and in Device Manager, the controller is alive and software recovery has a chance. If the disk is not detected at all, or makes a mechanical noise, stop and use a professional service instead of running a scan.

Record the disk model, capacity, and the approximate date of the last successful boot. These details help you choose the correct scan range and confirm that the recovered files come from the right volume.

Scan the Unallocated Space with Qiling

Qiling Deep Data Recovery can scan a disk whose partition entry is missing and rebuild the folder tree from the file records it finds. It reads the disk and writes the results to a different destination, so the affected space is not overwritten during the scan.

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Step 1. Choose the Partition Scan Mode

Select the mode that covers lost or unallocated partitions rather than the ordinary deleted-file scan. If the volume is visible but unreadable, choose the format or RAW-volume option instead.

Choose a partition recovery mode after the Windows 11 25H2 update

Step 2. Select the Affected Disk

Pick the physical disk, not a drive letter, and compare the capacity with Disk Management. If the partition disappeared from a secondary data disk, select that disk only; scanning every disk at once slows the task and makes the results harder to review.

Select the disk that shows unallocated space

Step 3. Recover to Another Disk

Review the rebuilt folders, preview a few documents and photos, then save the recovered files to an external disk or a different internal volume. Never save them back to the unallocated space you are trying to repair.

Recover files from the unallocated disk to another drive

Frequently Asked Questions

Did the 25H2 update delete my partition?

Usually not. The update can leave the partition table misread or the volume unreadable, while the data remains until it is overwritten.

Can I just create a new partition?

Not before recovery. Creating a partition writes new metadata over the old table and reduces the chance of rebuilding the previous volume.

What if the disk shows RAW instead of unallocated?

Use a file-system or format recovery scan. The partition exists, but its file system cannot be read by Windows.

How long should I wait before scanning?

Start as soon as the disk is stable. Waiting does not improve the odds, and continued use of the drive lowers them.

For the wider symptom, see hard drives missing after a Windows update.

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